The experimentally determined pressure drops due to a sudden contraction in two-phase flow in round pipes is given as a function of system pressure, flowing mixture quality, contraction area ratio, and mass velocity. The theoretical equation derived for the resulting pressure drop is ΔPc=G322gcρ¯[1−σ2+K¯TPC] where KTPC is a parameter independent of mass velocity. This parameter was evaluated for three different two-phase flow models. It is shown that the fog-flow (homogeneous) model gives the best correlation of data over the whole range of conditions studied. The range of pressures studied was 200–500 psia; the area ratios varied from 0.144 to 0.398; the mass velocity varied from 0.52 × 106 to 4.82 × 106 lb/hr-ft2. The fluid used in this study was water.